Unrecognized Myocardial Infarction Research Articles

Unrecognized Myocardial Infarction: Epidemiology, Clinical Characteristics, and the Prognostic Role of Angina Pectoris: The Reykjavik Study

To evaluate the incidence, prevalence, characteristics, and prognosis associated with clinically unrecognized myocardial infarction as diagnosed by electrocardiographic changes. Prospective, population-based cohort study with 4- to 20-year follow-up. Icelandic Heart Association Preventive Clinic. 9141 men residing in the Reykjavik area who were born between 1907 and 1934. Patients were assigned to categories of coronary heart disease at first visit on the basis of hospital records, Rose chest pain questionnaire, standardized 12-lead electrocardiogram, and history and physical examination. Incidence and prevalence of unrecognized myocardial infarction were determined, survival was measured, and causes of death were determined from death certificates and autopsy records. Prevalence was strongly influenced by age. Nearly undetectable in the youngest age group, it increased to more than 5% in the group aged 75 to 79 years. Incidence was almost zero up to age 40, then increased steeply to more than 300 cases per year per 100,000 persons at age 60, and decreased with age after age 65. Ten- and 15-year survival probabilities were 51% and 45%, respectively, and were similar to those for patients with recognized myocardial infarction. One third of men with unrecognized and 58% of men with recognized myocardial infarction had a history of angina pectoris (P < 0.001). Angina pectoris had a greater effect on coronary heart disease mortality in the former group than in the latter. The risk ratio for unrecognized myocardial infarction was 4.6 without angina (95% CI, 2.4 to 8.6) and 16.9 with angina (CI, 9.4 to 30.3); the risk ratio for recognized myocardial infarction was 6.3 without angina (CI, 3.7 to 10.6) and 8.5 with angina (CI, 5.8 to 12.6). At least one third of all myocardial infarctions were unrecognized. Prognosis and risk factor profiles for patients with recognized and unrecognized myocardial infarction were similar. Although those with unrecognized myocardial infarction were less likely than those with recognized myocardial infarction to have a history of angina pectoris, angina in these cases was usually associated with ischemic electrocardiographic changes and a poor prognosis, suggesting severe coronary heart disease.

Psychosocial Correlates of Unrecognized MI

Epidemiologic studies have shown that unrecognized myocardial infarctions are common and have serious prognostic implications. This study compared the psychosocial characteristics of 40 patients who sought treatment for a documented MI …

Prognosis after the onset of coronary heart disease. An investigation of differences in outcome between the sexes according to initial coronary disease presentation.

Differences exist between men and women in prognosis after the onset of coronary heart disease (CHD). All Framingham Heart Study subjects with the onset of clinically apparent coronary disease from 1951 through 1986 were studied to compare prognosis in men and women according to CHD presentation. Coronary disease presentations included angina, coronary insufficiency (unstable angina), recognized myocardial infarction, unrecognized myocardial infarction, and coronary death. Less than 1% of subjects were lost to follow-up for overall mortality. Cox modeling was used to examine the sex differences in outcome for each coronary presentation. New nonfatal coronary disease developed in 750 men (mean age, 63 years) and 583 women (mean age, 67 years). After onset of angina, men were at greater risk than women for myocardial infarction (hazards ratio [HR], 2.20; 95% confidence interval [CI], 1.45 to 3.34) and coronary death (HR, 2.11; 95% CI, 1.32 to 3.36) after adjustment for age and coronary disease risk factors. After a recognized myocardial infarction, there was a trend toward greater risk for overall mortality in women than men after adjustment for age and risk factors (HR, 0.75; 95% CI, 0.53 to 1.08). In contrast, after an unrecognized myocardial infarction, men were at increased risk for death compared with women (HR, 2.01; 95% CI, 1.28 to 3.15). Women fare at least as poorly as men after recognized myocardial infarction, whereas women have a more favorable outlook than men after the onset of angina or unrecognized myocardial infarction. The favorable outcome in women after angina and unrecognized myocardial infarction is due, in part, to greater misclassification of these coronary events in women than in men.

Potency of vascular risk factors as the basis for antihypertensive therapy.

Hypertension is a powerful predisposing risk factor for cardiovascular disease at all ages and in both sexes. Epidemiological assessment indicates the largest risk ratios for stroke and congestive heart failure (CHF), but coronary heart disease (CHD) is the most common and most lethal sequela of hypertension. Examination of the risk of cardiovascular sequelae in the hypertensive population indicates that this is not uniform and varies over a 10-fold range, depending on the associated risk factors. Systolic pressure merits greater consideration than the diastole pressure because isolated systolic hypertension is a powerful cardiovascular risk at all ages. Furthermore, recent trials have indicated the benefit of therapy for systolic-based hypertension in the elderly, even using a diuretic, for coronary disease as well as stroke. Persons with hypertension have a high prevalence of associated cardiovascular risk factors, including elevated cholesterol, reduced HDL-C, diabetes, left ventricular hypertrophy (LVH), and obesity. About 9% under the age of 65 years have an associated overt cardiovascular disease; above age 65 about 30% are so afflicted. Each of these risk factors can double the risk associated with hypertension. Because they are so common, a large fraction of the disease sequelae of hypertension is attributable to these associated risk factors. The high risk of coronary disease in hypertensive patients is concentrated in those with a high total/HDL-cholesterol ratio, impaired glucose tolerance, high fibrinogen, ECG abnormalities, and cigarette smokers. Stroke risk in hypertensive persons is concentrated in those with cardiovascular disease, diabetes, atrial fibrillation, LVH and cigarette smoking.(ABSTRACT TRUNCATED AT 250 WORDS)

Hypertension: cardiovascular implications in a cohort of old old.

To examine the prevalence and cardiovascular implications of hypertension in advanced age. Prospective non-interventional study of a fixed cohort of very elderly subjects. The subjects were 488 community-dwelling volunteers. Mean age at entry was 79 years (range 75-85). All subjects were ambulatory, non-demented, and free of terminal illness at baseline. Participants were evaluated at the gerontology department of an urban medical school. Cardiovascular morbid and mortal events that were followed included fatal and non-fatal myocardial infarction, fatal and non-fatal stroke, and death. Prevalence of unrecognized myocardial infarction defined by electrocardiographic changes was also assessed. When hypertension was defined by history, current use of medications, or measured elevations in blood pressure, 78% of the subjects could be considered hypertensive. Univariate analysis showed an increased incidence of strokes in subjects with measured hypertension (P = 0.04). Subjects with elevated blood pressure (untreated) were more likely to develop clinically unrecognized myocardial infarction (P = 0.017). Multivariate survival analysis showed hypertension to be a modest predictor of overall cardiovascular disease (P = 0.067) but not of all-cause mortality. Left ventricular hypertrophy was a predictor of cardiovascular disease (P = 0.013) and all-cause mortality (P = 0.008). Age remained a significant risk factor for these endpoints, even in the very old. Isolated systolic hypertension was analyzed separately and in univariate analysis was a risk factor for stroke but not other cardiovascular morbidity. Hypertension at advanced age remains a modestly important risk factor in the development of cardiovascular disease.

Demographics of the prevalence, incidence, and management of coronary heart disease in the elderly and in women.

Cardiovascular disease constitutes an expanding problem in the elderly because of the increasing size of the aged population. Atherosclerosis, hypertension, and diabetes are responsible for the predonderance of cardiovascular disease, which causes 70% of all deaths beyond age 75. Coronary heart disease (CHD) is the most common and most lethal cardiovascular event in both sexes, exacting a large toll in disability and deteriorated quality of life in old age. Unrecognized myocardial infarctions are especially common and are as serious as symptomatic infarctions. beyond age 65, women are as vulnerable to cardiovascular death as men. The predisposing modifiable risk factors for coronary disease, stroke, peripheral arterial disease, and cardiac failure are similar in young and old and in men and women. These include hypertension, dyslipidemia, impaired glucose tolerance, physical indolence, and cigarette smoking. An attenuated risk ratio for some risk factors is offset by a greater incidence of cardiovascular events in advanced age so that the attributable risk and the potential benefit of treatment rise with age. Because the major risk factors predict CHD as efficiently in the elderly as in the young, and the decline in cardiovascular mortality has included the elderly, preventive efforts in the elderly may have substantial potential benefit. At advanced age, total cholesterol levels are considerably higher in women than in men. Some 10 million elderly, two-thirds of whom are women, may require investigation and treatment for elevated lipid levels, as determined by National Heart, Lung, and Blood Institute (NHLBI) guidelines. Because of the preponderance of women in the elderly population, trials of the efficacy of correcting risk factors in general, and lipids in particular, should include women.

The epidemiology of impaired glucose tolerance and hypertension

Epidemiologic research indicates that glucose intolerance and hypertension are interrelated phenomena, each powerfully predisposing to atherosclerotic cardiovascular disease. Both diabetic and hypertensive patients have greater amounts of atherogenic risk factors, including dyslipidemia, hyperuricemia, elevated fibrinogen, and left ventricular hypertrophy. Diabetic persons have an increased prevalence of hypertension (50%), and glucose intolerance is more common in hypertension (15% to 18%). Both share a strong relationship to excess weight, but the excess of hypertension in diabetic persons occurs in both lean and obese subjects. Diabetes doubles the risk of hypertension associated with overweight. The risk of coronary disease, stroke, and peripheral arterial disease increases with increasing blood pressure to the same degree in diabetic persons as in nondiabetic persons, but at any level of blood pressure, diabetic persons have a doubled risk of these outcomes. Both diabetic and hypertensive patients are particularly prone to silent or unrecognized myocardial infarctions. Greater efforts at primary prevention of both hypertension and diabetes are clearly needed, including efforts at weight control, exercise, limitation of salt intake, and control of blood lipid levels. In either diabetic or hypertensive candidates for cardiovascular disease, optimization of the chances of avoiding sequelae requires a comprehensive multifactorial approach. Prevention requires more than normalization of either the blood sugar or blood pressure. Rational preventive measures must also include weight reduction, a fat-modified diet, cessation of smoking cigarettes, raising high-density lipoprotein, lowering low-density lipoprotein, and reduction of fibrinogen. Hypertension, obesity, insulin resistance, hyperinsulinemia, hypertriglyceridemia, and low high-density lipoprotein cholesterol tend to coexist. All these factors accelerate atherogenesis and may be responsible for the increased propensity of either diabetic or hypertensive patients to develop coronary heart disease. Treatments that worsen these features in hypertensive or diabetic patients are best avoided.

Prevalence, incidence and prognosis of recognized and unrecognized myocardial infarction in persons aged 75 years or older: The Bronx Aging Study

The prevalence, incidence and prognosis of recognized and unrecognized Q-wave myocardial infarction (MI) was assessed in an 8-year prospective study of 390 community-based subjects (age 75 to 85 years at entry, mean 79 years). Subjects were studied at baseline and with annual follow-up electrocardiographic (ECG) exams. At baseline, 7.9% had a history of MI without ECG evidence, 6.4% had ECG evidence of Q-wave M8I without clinical history, 4.1% had both clinical history and ECG evidence and 81.5% had neither history nor ECG evidence (control subjects). After an average follow-up period of 76.2 months, the total mortality rate was 5.9 100 person-years for subjects with some evidence of MI at baseline versus 3.9 in the control group (p = 0.059). The incidence of cardiovascular disease in subjects with evidence of MI was 8.8 100 person-years versus 4.7 among control subjects (p = 0.002). During the follow-up period, 115 new Q-wave MIs occurred (50 unrecognized, rate 2.4 100 ; 65 recognized, rate 3.2 100 ). There was no difference in mortality and morbidity outcome between subjects with recognized and unrecognized MIs. Those with only a history of MI at baseline had a threefold greater risk of a new MI (recognized and unrecognized) than the control group (p = 0.003). Unrecognized Q-wave MI is a common occurrence in the “old old” with subsequent morbidity and mortality prognosis comparable to that of recognized MI. History of MI alone in this age group is also associated with an increased risk of MI, suggesting the need for better diagnostic markers of myocardial ischemia in the old.

The Incidence and Prognosis of Unrecognized Myocardial Infarction

To the Editor.—Yano and MacLean have marred a very good article1on unrecognized myocardial infarction with misleading terminology that has been widely rejected—equating with infarction.2While most, but not all, infarctions probably are transmural, many non—Q-wave infarctions also are transmural. At least since 1983,2,3most medical publications do not accept equating an electrocardiographic pattern with an anatomic pattern as in the past. Terminologic disputes are often quibbles, but not when concepts are involved. Throughout their text the authors equate parenthetically as transmural and non— Q-wave as subendocardial, which is plainly wrong. (The parentheses might sanitize this presentation if they were explained as indicating outmoded usage.) What weactually seeon electrocardiograms is abnormal Q waves or their absence and that is the appropriate mode of reporting. The knowledgeable reader will know that many myocardial infarctions may be transmural. The less knowledgeable

The incidence and prognosis of unrecognized myocardial infarction

The incidence and prognosis of unrecognized myocardial infarction

The Incidence and Prognosis of Unrecognized Myocardial Infarction in the Honolulu, Hawaii, Heart Program

The incidence of clinically unrecognized myocardial infarctions among 7331 Japanese-American men in Hawaii, aged 45 to 68 years and free of coronary heart disease at entry, was studied on the basis of electrocardiographic changes between successive examinations during 6 years of follow-up. The proportion of asymptomatic myocardial infarction accounted for 33% of transmural (Q-wave) myocardial infarctions identified by temporal changes on electrocardiogram and 22% of all nonfatal infarctions ascertained by either repeated examinations or hospital surveillance. The 10-year prognosis of unrecognized infarction, in terms of mortality from all causes, cardiovascular disease, and coronary heart disease, was worse (with risk ratios of 1.5 to 1.7) than that of recognized infarction, even after adjusting for age and other possible determinants, although the differences were not statistically significant. These findings suggest that regular health check-ups with an electrocardiogram would be important to detect asymptomatic myocardial infarction and to increase the opportunity of taking secondary preventive measures. However, the conclusion should await further studies based on intervention trials to determine the comparative effects of the secondary prevention on the prognosis of clinically recognized vs unrecognized infarction.

The incidence and prognosis of unrecognized myocardial infarction in the Honolulu, Hawaii, Heart Program

The incidence and prognosis of unrecognized myocardial infarction in the Honolulu, Hawaii, Heart Program

New coronary events at four-year follow-up in elderly patients with recognized or unrecognized myocardial infarction

Eighty-three (35%) of 237 women and 130 (28%) of 469 men with initial myocardial infarction (MI) in the Framingham Study had unrecognized MI, which was detected by electrocardiogram. 1 At 10-year follow-up, coronary artery disease (CAD) death incidence, sudden coronary death incidence and recurrent MI incidence were similar among men with unrecognized or recognized MI. 1 CAD death incidence and sudden coronary death incidence were similar among women with unrecognized or recognized MI. However, the incidence of recurrent MI was greater among women with recognized MI than among women with unrecognized MI (p < 0.05). We 2 reported in a retrospective study that 78 (68%) of 115 elderly patients in a long-term health care facility with either documented clinical history of MI or current electrocardiographic evidence of Q-wave MI had unrecognized MI detected by routine electrocardiogram. We performed a prospective study to determine the incidence of new coronary events in these elderly patients with recognized or unrecognized MI.

Silent myocardial ischemia in the aged: a retrospective study from the evaluation of necropsy hearts.

The diagnosis of silent myocardial ischemia in the aged remains controversial. In this study to evaluate the basic state of silent ischemia in the aged, a total of 972 consecutive autopsy cases (mean 79.0 yrs of age) were analyzed in terms of coronary atherosclerotic diseases. The following results were obtained: (1) Severe coronary occlusive lesions simultaneously detected in the three major coronary arterial branches were found in 85 cases (8.7%), of which 10 (12%) had neither history of angina nor myocardial infarction (MI), which may correspond to one representation of silent ischemia. (2) There were 218 cases of MI (22.4%), of which 106 (49%) were never documented to have MI during life. The latter may correspond to unrecognized MI. It was considered to be caused by 1) small or middle-sized MI in 66 cases and 2) lateral or nontransmural MI in 29 out of 40 large MI cases (more than 4.9 cm in diameter). (3) 30 cases (54%) out of 56 fresh and large MI with a correct diagnosis revealed no chest pain. This is an incidence of painless MI in the aged. This painless group showed a significant difference in the incidence of a correct diagnosis of MI (51% vs 89%), combined arrhythmia (47% vs 79%) and the association of CVD (47% vs 11%) compared with chest pain group.

Diagnostic criteria for hospitalized acute myocardial infarction: the Minnesota experience.

Standardized diagnostic algorithms are needed for systematic surveillance of hospitalized acute myocardial infarction (AMI). Ambiguities in diagnostic classification are resolvable to the extent that objective information is available in the hospital chart. In this study of diagnostic algorithms, serum cardiac enzyme levels, especially creatine kinase total (CK-TOT) and creatine kinase myocardial band (CK-MB) isoenzyme, were most closely correlated with the physician-reviewer diagnostic assignment used for validation; chest pain and electrocardiographic findings were less closely correlated. In addition, a close relationship was noted between the clinician's diagnostic impression and testing procedures and the final hospital discharge diagnosis. Thus, the algorithm should include discharge diagnosis as a classification element. The algorithm for cases discharged as acute myocardial infarction should be very sensitive, tending to call cases acute myocardial infarction. Other discharge diagnoses may harbour some clinically unrecognized myocardial infarction cases; however, the algorithm for such cases should be restrictive and specific to minimize false positives. These findings indicate optimal ways of combining clinical characteristics to most completely and accurately identify cases of acute myocardial infarction based on hospital records examined in retrospect.

Usefulness of silent myocardial ischemia detected by ambulatory electrocardiographic monitoring in predicting new coronary events in elderly patients

Unrecognized myocardial infarction (MI) detected by electrocardiogram (ECG) occurred in 83 of 237 women (35%) and 130 of 469 men (28%) with initial MI in the Framingham study. 1 Unrecognized MI had as serious a prognosis as recognized MI in that study. 1 In our 1985 study, 2 we reported that unrecognized Q-wave MI detected by ECG occurred in 78 of 115 elderly patients (68%) with MI in a long-term health care facility. After instructing staff physicians on the different presenting symptoms of MI in elderly patients, the incidence of unrecognized MI detected by ECG in a prospective study was 23 of 110 MIS (21%). 3 Silent myocardial ischemia detected by ambulatory ECG monitoring is common during daily life in asymptomatic patients with coronary artery disease (CAD) and positive treadmill exercise tests. 4 In unstable angina, 80% of ischemic episodes are silent. 5 Abnormalities in regional and global left ventricular wall motion are similar in patients with CAD, with and without silent ischemia. 6 Rubidium-82 positron-emission tomographic studies have demonstrated reduced myocardial perfusion during episodes of silent myocardial ischemia detected by ambulatory ECG monitoring in patients with CAD. 7 The prognosis of asymptomatic silent ischemia in patients with CAD depends on the extent of CAD and left ventricular dysfunction. 8 The prognostic value of silent ischemia detected by ambulatory ECG monitoring has been reported in patients with unstable angina, 9–11 in high-risk postinfarction patients 12 and in patients with stable CAD. 13,14 We performed a prospective study (1) to determine the prevalence of silent ischemia in elderly patients with CAD, patients with systemic hypertension, valvular heart disease or cardiomyopathy, and in patients with no evidence of heart disease, and (2) to correlate silent ischemia with cardiac events at 26-month follow-up in these groups of patients.

Silent myocardial ischemia in asymptomatic survivors of unrecognized myocardial infarction and matched controls

Although silent myocardial ischemia (SI) occurs frequently in patients with angina and is of prognostic significance, little is known of its occurrence in other subgroups. We assessed the incidence of SI in offspring of Framingham Heart Study (FHS) patients following unrecognized myocardial infarction (UMI) and in controls without MI but who were matched for age, sex, hypertension, diabetes, smoking, and total cholesterol at entry into the FHS. Of the 20 UMI patients, six had died and one with left bundle branch block was excluded. The remaining 13 UMI patients and 26 control patients underwent 24-hour ambulatory electrocardiographic monitoring (AECG) for SI. Two patients (one from each group) with angina were excluded from the AECG analysis. Only two (15.4%) of the UMI patients and two (7.7%) of the control patients had any AECG evidence of SI. These preliminary results suggest that routine monitoring for SI is not indicated in asymptomatic long-term survivors of UMI or in asymptomatic patients without prior MI but with otherwise similar risk profiles.

Prevalence of presenting symptoms of recognized acute myocardial infarction and of unrecognized healed myocardial infarction in elderly patients

Eighty-three of 239 women (35%) and 130 of 469 men (28%) with initial myocardial infarction (MI) in the Framingham study had unrecognized MI, which was detected by electrocardiogram. 1 We reported that 78 of 115 elderly patients (68%) in a long-term health care facility with either documented clinical history of MI or current electrocardiographic evidence of Q-wave MI had unrecognized MI detected by routine electrocardiogram. 2 Elderly patients may have symptoms other than chest pain associated with MI. 3–6 We performed a prospective study in a long-term health care facility to determine the prevalence of presenting symptoms of recognized acute MI and of unrecognized healed new MI detected by electrocardiogram in elderly patients who developed documented MI.

Frequent episodes of silent myocardial ischemia after apparently uncomplicated myocardial infarction

Frequent episodes of silent myocardial ischemia were documented in two patients, one with recognized and one with unrecognized prior myocardial infarction. Neither patient had symptoms after the infarction, but both demonstrated silent myocardial ischemia on exercise testing, which prompted further study with 48 hour ambulatory electrocardiographic (Holter) recordings. In each patient, heart rate recorded with the Holter monitor during the ischemic episodes was usually less than that observed during ischemia precipitated by exercise testing. This suggests that increased vasoconstrictive tone may play a role in silent ischemic episodes occurring during daily activities.

A prognostic comparison of asymptomatic left ventricular hypertrophy and unrecognized myocardial infarction: The Framingham study

In 30 years of follow-up in the Framingham study, routine biennial ECG examinations revealed 315 subjects with ECG-LVH and 164 with unrecognized ECG-MI without previous cardiac explanation. Among subjects initially free of clinically evident coronary heart disease and both ECG abnormalities, the incidence of ECG-LVH was about double that of ECG-MI. Both events exhibited a male predominance and hypertensive subjects were more vulnerable to each. In subjects with asymptomatic ECG-LVH and ECG-MI, the 10-year, age-adjusted incidence of clinical coronary heart disease was greater than the rate experienced by the general Framingham sample. Rates for ECG-LVH were almost as large as those for ECG-MI. Cardiac failure and stroke also occurred more frequently among subjects with either ECG abnormality, and rates for ECG-LVH exceeded those for ECG-MI. Death from coronary heart disease, and sudden death in particular, was also increased two- to fourfold with similar risks for ECG-LVH and ECG-MI. ECG-LVH carried a significantly greater risk than ECG-MI for cardiovascular deaths in women. These findings suggest that ECG-LVH and ECG-MI are similar subclinical events with respect to predisposing characteristics and prognosis for subsequent overt cardiovascular disease including clinical manifestations of coronary heart disease.